Transcript for Swimmers Sickened by Mystery Illness at Washington Lake

There's something in the water at -- keeping visitors to one park in Washington State on their toes. 84 people have gotten sick after swimming and horseshoe lake in southeast Washington and the number may very well increase health officials suspect. -- -- -- That is leading to intense stomach problems vomiting or even worse for some beach goers. So far park officials have posted signs -- closed off entrances to the beach shutting down the popular lake. And most visitors have taken note. It's a bit of a -- reform they get to they'd love to be out on the water toys and having a blast than we feel like a conservative approach is -- Local officials are waiting for test results to come back to see if it's bacteria or a virus that's sending dozens homesick.

This transcript has been automatically generated and may not be 100% accurate.

Now Playing: Kellyann Petrucci shares how to blast belly fat and slim down in 10 days

Now Playing: What to know about SCAD, a leading cause of heart attacks for young women

Now Playing: Increasing number of children killed by flu epidemic

Now Playing: The CDC says some rapid flu tests are only 50-70% accurate

Now Playing: Top female Olympians pledge brains to concussion research

Now Playing: Fetal alcohol syndrome in children up to 10 times more common than experts thought

Now Playing: {{itm.title}}

{"id":24569267,"title":"Swimmers Sickened by Mystery Illness at Washington Lake","duration":"0:47","description":"A norovirus is suspected of sickening people who swam in Horseshoe Lake over the weekend.","url":"/Health/video/swimmers-sickened-mystery-illness-washington-lake-24569267","section":"Health","mediaType":"default"}